Abstract

Aim

Early tumor shrinkage (ETS) is associated with long-term outcome in patients receiving chemotherapy plus cetuximab, which was investigated in CRYSTAL and OPUS trials. CLIME study (NCT01322178) was designed to observe whether the addition of targeted drug in first line further increases the curative resection rate and improves long-term survival in KRAS wide-type colorectal liver limited metastases patients in China. This retrospective analysis aims to show the impact of ETS on long-term outcome in CLIME study.

Methods

Radiologic assessments at week 8 were used to calculate the relative change in the sum of the longest diameters of the target lesions. A 20% decrease cutoff value was selected as a dichotomization threshold for further investigation. Outcome measures were objective response rate (ORR), curative resection rate and progression-free survival (PFS). Cox regression models were used to quantify individual changes in tumor size over time and to relate these changes to PFS.

Results

From the ITT cohort (100 cases), 92 patients were available for ETS assessment and 70 pts achieved ETS (76.1%). These data were comparable with quantitative analysis of ETS in CRYSTAL and OPUS trials (table 1). Longer PFS was observed in patients who achieved ETS as compared to patients with no-ETS (10.9m vs. 6.2m, HR 0.203, 95%CI 0.087-0.473, P < 0.0001). In patients who achieved ETS, ORR was much higher than in patients with no ETS (81.4% vs. 13.6%, p < 0.0001). Cetuximab-related AEs (any grade and grade 3/4) seemed to be more common in patients who achieved ETS.